1. Field of the Invention
One or more embodiments of the invention are related to the field of positioning systems, data processing systems and communication systems. More particularly, but not by way of limitation, one or more embodiments of the invention enable a local positioning and response system configured to transmit signals such as two or more shaped beams from at least one transmitter unit and devices that receive the shaped beams. The devices determine their local position in a defined area, such as a stadium or other venue that may not enable access to satellite based positioning signals. The devices determine their individual responses based on their local position and on broadcast messages that may define aggregate responses for a group of devices in the area. A response may include, but is not limited to emitting a physical signal such as a light, sound, message of any type based on the local position determined by the device and the broadcast message.
2. Description of the Related Art
With the advent of handheld computing devices such as smart phones, Personal Digital Assistants (PDAs), tablet computers, etc., a need has arisen to enable those devices to determine their position in space. A large number of techniques have been devised to accomplish this task, including Global Positioning System (GPS) and similar technologies that utilize triangulation based on relative signal delays to multiple transmitters along with very sophisticated computational algorithms. In addition, other techniques include received combination power based methods used in some cell phones, and various other more esoteric techniques, such as ultrasonic GPS, for example. While fairly successful in determining approximate location, these methods suffer from a number of limitations. GPS requires a “clear sky”, i.e. clear line of sight to multiple satellites along different directions. The received signals are so weak that even a tree canopy tends to attenuate the signals enough to preclude accurate positioning. Indoors, the signal attenuation prevents GPS from working altogether. Some other methods, such as cell phone based techniques can operate indoors, where signal strength can be much higher due to proximity of the transmitters and much higher available electrical power on the ground. This technique is limited by the fortuitous placement of antenna towers, as well as by the sensitivity of the received signal strength to absorption along the signal path, reflections, and diffraction. These effects render this technique of positioning inaccurate, limiting the accuracy in dynamic and unpredictable ways.
Recently a need has been recognized to enable positioning of simple inexpensive devices in a fairly limited area, a venue such as a large hall, a warehouse, a parking lot, or a stadium. The position of interest is in a virtual relative coordinate system tied to the venue as opposed to global geocentric coordinates, which include latitude and longitude. The desired accuracy ranges for local position systems depend on the desired application, for example from around 1 foot, or 0.3 m, for determining the position of a person-sized object), to around an inch, or 2.5 cm, for tracking smaller objects like packages or communicating with sensors, lights, etc. There are no known existing systems that provide accurate local positioning in a limited area with inexpensive devices.
In addition, many applications require that a potentially large number of devices in a limited area create a response that is observable in aggregate. For example, all devices in a house may be commanded to turn off, with reduced power consumption as the observable aggregate response. As another example, spectators at a football game may be given light-emitting devices, and the sponsors of the game may desire that these lights be coordinated to emit stadium-sized images that are visible from television cameras. Technologies exist to provide communication between central systems and a network of devices; however these systems generally use point-to-point communication and require significant bandwidth as well as significant power and cost in the devices. Further issues such as privacy and anonymous addressing of the devices make mobile phones and other handheld devices less desirable for this application.
The number of usable devices that may respond to system messages is growing dramatically, and current system architectures are not suited to handle this growth. For example, with the advent of inexpensive radio transceivers and microprocessors, an increasing number of common household items are attaining both some computer intelligence and wireless connectivity. This trend is expected to continue and speed up as electronics technology advances and electronic components become cheaper. In the not so distant future, an average house may contain hundreds of Wi-Fi-connectable items. It is conceivable that in the near future, all items of non-negligible value may be equipped with rudimentary wireless transceivers and some processing power. All these thousands of transceivers will occupy the same limited portion of the radio spectrum and thus the data rate available for communicating with any individual unit will become vanishingly small, in effect debilitating the wireless communicating capability of the devices.
In areas greater than the size of a house, the number of devices may be even larger. Potentially there may be a need to communicate with millions of such devices over fairly modest bandwidth resources. Existing system architectures, which are based largely on point-to-point communication, cannot handle these requirements. Moreover the systems that provide location-awareness, such as GPS, require expensive transmitters and receivers and are ill-suited for widespread application and low-cost, low-power devices.
For at least the limitations described above there is a need for a local positioning and response system, which provides an architecture and a system solution for low-power, low-cost devices to determine their position and generate responses without requiring large amounts of network bandwidth for communication.